Field of the Invention
The present invention relates to a sheet processing apparatus, a method of controlling the same, and a computer-readable storage medium.
Description of the Related Art
In recent years, creasing processing is increasingly being applied to a printed material on which bookbinding such as case binding is performed using an image forming apparatus such as a digital copying machine or a multi-function peripheral. Creasing is processing for adding a crease to a printing sheet (hereinafter referred to as media) prior to folding processing being applied. For example, in the case of case binding, there are cases in which a creasing is applied to the edge of the spine of the case binding. By doing this, the fold on the edge of the spine becomes more attractive, and the quality of the resulting document (bookbinding product) that is bound can be raised.
Also, creasing is used to add a crease to a position at which a user wishes to insert a fold. For example, often media having a large paper thickness is used for a cover when case binding. So, there is an advantage of making it easier for the user to open the cover by adding a crease to the cover in advance. Furthermore, because a cover and inner sheets are glued in case binding, it is easy for the cover to be peeled off if too much force is applied to a position that is glued when the cover is opened. So, by adding a crease at a location away from the position that is glued, a load is not put onto the glued position even when the user opens the cover, and there is the advantage that this can prevent the cover being easily peeled off. Hereinafter, a crease applied to a position at which a user wishes to insert a fold, as described above, is described as a crease for folding.
For a crease for folding, the position should be determined considering the convenience of the user. For example, if the edge of the spine of the case binding and the position of the crease for folding are too close, it will be difficult for the user to open the cover when holding the case bound book in his or her hand. Also, if the edge of the spine of the case binding and the position of the crease for folding are too separated, the contents of the first page of the book will be overlapped by the position of the crease for folding, and so the contents of the page will be difficult to see. In other words, the position of the crease for folding should be determined for each case binding, and the crease for folding is not something that can be applied at a fixed position.
Also, normally, an edge of the media is made to be a basis position, and it is necessary to designate the creasing position to be at a position that is separated from the basis position by a predetermined length. This is because the creaser apparatus is configured so as to detect a leading edge of a sheet, and to apply the creasing processing to a position that is an instructed length from the leading edge position.
An approach to designating the position of the crease for folding is described in Japanese Patent Laid-Open No. 2013-119451, for example. Using this approach, it is possible to apply creases for folding to a cover of a case binding, where the number of creases and the positions of the creases are designated by an operator.
In the approach described in the foregoing Japanese Patent Laid-Open No. 2013-119451, it is possible to apply the creases for folding in accordance with positions that the operator designated and a number that the operator designated, but it is necessary for the operator himself to determine the positions of the folding creases having understood the length of the media. However, normally, it is often the case that the position of the crease for folding is considered under the basis of the length from the edge of the spine cover. For this reason, when the approach of Japanese Patent Laid-Open No. 2013-119451 is used, the operator must determine the position of the crease for folding by calculation having understood the length of the media, and this is cumbersome.